Method of casting printing slugs



Patented June 23, 1925.

UNITED I STATES VPATENT'I'OFF'ICE.

JAMES LEWIS, or OTTAWA, ONTARIO, cANAnA.

'METHOD OF cAsT NG PRINTING sLUes.

No Drawing.

To all whom it may concern Be it known that I, JAMES LEWIS, a subject of the King of Great Britain, and resident ofthe city of Ottawa, in the Province of Ontario, Dominion of Canada, have invented certain new and useful Improvements in the Method of Casting Printing Slugs; and I do hereby declare that the following is a full, clear, and exactdescription thereof.

The object of the present invention is to provide a new and improved method of expeditiously and economically making cast slugs for printing reproductions of printed matter, signatures such as appear on stocks, bonds and the like and pictorial representations.

Heretofore in printing Work of this kind particularly in the printing of signatures and pictorial representations in large quantities it has been and still is the practice generally to make a large number of electrotypes having the design, to be reproduced, inrelief. This method has proved both costly and slow and it is highly desirable to provide a method by which re productions may be printed in large quantities at a comparatively low cost.

Attempts to solve the difficulty have been made in the past by making steel male dies of the designs to be reproduced and with the dies forming in brass and other suitable metal, matrices in which slugs were cast. These attempts failed however to overcome the difliculty owing to the high cost of making the steel dies.

The present invention provides a solution of the problem by making it possible to make at a minimum cost and in a comparatively short time any desired number of slugs having. in their printing faces the design in relief, to be reproduced.

In carrying out my improved method a zinc line etching is first made from the copy which it is desired to reproduce. This is accomplished by coating the zinc with a bichromated fish glue or enamel and the copy photographed thereon. This photograph is then developed and the zinc etched with acid which bites away all portions of the zinc not coated with the enamel, leaving the design in relief.

The etching thus produced is then placed in an electro-plating bath and copper, brass r any other suitable metal is deposited on Applicationfiled March 11, 1925, Serial No. 14,780. I

the zinc by electrolysis to a depth of approximately one sixteenthof an inch orto whatever depth may be required for'the particular kind of type casting machine with which the casting is to be done.

After the desired depth of metal has been deposited the zinc is removed, leaving an intaglio design in the electro-plate constituting a matrix. The zinc is removed by subjecting it toatemperature higher than its melting point of 419 centigrade and considerably lower than the melting point of the metal deposited thereon. The melting points of the copper and brass are respectively1083 centigrade so that the melting of the zinc in a gas furnace may be readily effected without injuring the matrix when composed of either of the former metals. Any other metal employed should have a melting point in the vicinity of the melting points of these metals.

In order to more readily obtain the separation of the zinc from the matrix during the heating process, graphite may be mixed with the enamel which is deposited on the zlnc.

After the zinc has been removed the matrix is backed by any suitable reinforcing metal and is then ready for use in the casting operation. This may be carried out in any desired manner in any of the wellknown type casting machines.

From the foregoing it will be seen that it is possible to cast any desired number of slugs bearing in relief the design sought to be reproduced from the one matrix, the cost of making which is comparatively small, and furthermore that the reproductions printed from the slugs will be precise copies of the subject-matter which it is desired to reproduce.

What I claim is as follows 1. The method of casting printing slugs and the like consisting in making a zinc etching, making an intaglio impression in a suitable metal with the etching, and utilizing said impression as a matrix for the casting of printing slugs.

2. The method of casting printing slugs and the like consisting in making a zinc etching, electro-plating the zinc etching with a metal having a higher melting point than the melting point of the zinc; separating the zinc etching from the electrO-plating by subjecting it to a heat sufficient to melt the zinc but not sufficient to injure the elect ro-plating, and utilizing the latter as a matrix for the casting of printing slugs.

3. The method of casting printing slugs and the like consisting in making a zinc etching by coating the zinc with an enamel consisting of bichromated fish glue; photographing a design thereon and etching the zinc with a suitable acid to leave the design in relief; depositing a metal having a higher 'j'melting point than the melting pointof the zinc by electrolysis upon the zinc etching,

subjecting the whole to a heat suificient to separate the zinc from the metal without injuring the latter, and utilizing the intaglio impression thus formed in the metal as a matrix for the casting of printing slugs.

4. The method of casting printing slugs and the like consisting in making a zinc etching by coating the zinc with an enamel In testimony whereof I have signed my name to this specification in the presence of two wltnesses.

JAMES ,LEVIS.

WVitnesses IRENE POWELL, FRANK BARNES. 

